RADIAL VELOCITY AND INTENSITY MEASUREMENTS OF NIGHT SKY HBETA EMISSION LINE

Observations of the Hβ emission line in the night sky spectrum are presented. The measurements were made with a gas pressure-scanned Fabry Perot Interferometer from Testa Grigia (11,500 ft) in the Italian Alps, in November and December, 1967. Typical emission rates measured were 0.1-0.2 Rayleighs (R) and the line was found to be Doppler-shifted from the 4861.33 Å laboratory wavelength. The intensities and radial velocities of the Une are examined in various co-ordinate systems and it is shown that the total emission is probably due to the addition of two components; a 'galactic' and a 'non-galactic' contribution. The galactic contribution, due to nebular emission, dominates within ±15° latitude of the Milky Way; the emission at galactic latitudes greater than ±15° is interpreted as being non-galactic in origin and is discussed briefly in terms of both geocoronal and interplanetary emitting regions. © 1969.